                                 :similarity))
                           explorations)]
     (when (and (seq explorations) (< 0 (count explorations)))
-      (> (/ (apply + similarities) (count explorations)) *page-sim-thresh*))))
+      (try (> (/ (apply + similarities) (count explorations)) *page-sim-thresh*)
+           (catch Exception e nil)))))
 
 (defn enum-candidate-info
   "Uses the information sent and the snapshot info"

(def *sample-fraction* (/ 1 4))   ; fraction of links to look at
                                  ; before sampling

(def *xpath-hrefs*   (atom {}))   ; hold the unique hrefs for each xpath
(def *xpath-df*      (atom {}))   ; hold the df score for each xpath
(def *xpath-tf*      (atom {}))   ; per-page tf scores
(def *visited*       (atom
                      (set [])))  ; set of visited documents
(def *url-documents* (atom {}))   ; url -> body map

       (swap!
        *url-documents* utils/atom-merge-with set/union {a-link (set [body])})
       body)))

(defn sample
  ([urls host n]
